A system for fracturing and producing water circulation and treatment of deep coalbed methane wells in coal mines

Abstract

The invention relates to a fracturing and produced water circulation and treatment system for deep coalbed methane wells in coal mine fields, comprising a recycling unit, an oil removal tank and a biochemical treatment unit. The recycling unit comprises a mine water treatment unit and a plurality of well water treatment units connected in series in sequence; the mine water treatment unit comprises a static sedimentation tank and a fracturing water tank connected in sequence, the mine water discharged from the coal seam tunnel is discharged into the static sedimentation tank, and then discharged into the fracturing water tank after treatment, and can be used as fracturing water for the first coalbed methane well; the well water treatment unit comprises a reverse drainage tank, a static sedimentation tank and a fracturing water tank connected in sequence, the discharged water of the coalbed methane well is treated by the reverse drainage tank and the static sedimentation tank in sequence, and then discharged into the fracturing water tank, and can be used as fracturing water for the next coalbed methane well; the discharge water pipe of the last coalbed methane well is connected to a static sedimentation tank, an oil removal tank and a biochemical treatment unit in sequence.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment in coal mining areas, and in particular relates to a fracturing and produced water circulation and treatment system for a deep coalbed methane well in a coal mine field. Background Art

[0002] A large amount of mine water is generated during the construction and mining operations in coal mining areas. At present, the mine water is pumped to the ground and discharged after water treatment. In addition, coalbed methane wells in the coal mining area also face the problem of water use and production water treatment. The key to the development of deep coalbed methane resources is large-scale hydraulic fracturing reservoir transformation and drainage technology, which requires a large amount of water. At present, the areas in the country where deep coalbed methane resources are developed are mainly distributed in the eastern edge of the Ordos Basin, where water resources are extremely scarce. Therefore, the treatment and recycling of mine water, fracturing water and produced water in coal mining areas has become a problem faced by technical personnel in this field.

[0003] Since the mine water, fracturing water and produced water discharged from underground contain a certain amount of organic and inorganic pollutants, organic pollutants are mainly various water-soluble organic gases, liquids, solids in the coal seams, which dissolve in the water, and some underground oil-soluble substances, which will be discharged with the water; inorganic pollutants are mainly rocks and fragments in the coal seams, which are discharged with the water. Inorganic pollutants are mainly removed by precipitation and filtration. However, the viscosity of water containing organic pollutants is slightly larger, which reduces the sedimentation of inorganic pollutants and is easy to block filter settings. In addition, organic pollutants in sewage need to be removed by biochemical or chemical methods. The chemical method is to add chemical agents to react with organic pollutants to achieve the purpose of treatment, which is costly. The treatment speed of the biochemical method is slow and it is difficult to meet the large-scale water demand in coal mining areas. Summary of the invention

[0004] In view of the above problems, the present invention provides a fracturing and produced water circulation and treatment system for deep coalbed methane wells in coal mine fields, comprising a recycling unit, an oil removal tank and a biochemical treatment unit, wherein the recycling unit comprises a mine water treatment unit and a plurality of well water treatment units connected in series in sequence; the mine water treatment unit comprises a static sedimentation tank and a fracturing water tank connected in series in sequence, the mine water discharged from the coal seam roadway is discharged into the static sedimentation tank, and after treatment, is discharged into the fracturing water tank, which can be used as fracturing water for the first coalbed methane well;

[0005] The well drainage treatment unit includes a reverse drainage tank, a static sedimentation tank and a fracturing water tank which are connected in sequence. The drainage water of the coalbed methane well is processed in the reverse drainage tank and the static sedimentation tank in sequence, and then discharged into the fracturing water tank, which can be used as fracturing water for the next coalbed methane well.

[0006] The discharge pipe of the last coalbed methane well is connected to a static sedimentation tank, an oil removal tank and a biochemical treatment unit in sequence.

[0007] Optionally, a plurality of inclined guide channels are provided from top to bottom in the static sedimentation tank, which are zigzag and evenly arranged in the static sedimentation tank, and the guide channels are connected end to end; a water inlet pipe is connected to the higher end of the top guide channel to input sewage into the static sedimentation tank; a water outlet section is provided at the connection of two adjacent guide channels, and a water outlet hole is provided on the side of the water outlet section to discharge part of the water in the guide channel to the static sedimentation tank for oil-water-solid separation, and the other part of the water continues to flow to the next guide channel;

[0008] The oil removal tank includes a primary separation zone, a secondary separation zone and a tertiary separation zone from bottom to top. A number of vertical drive diversion cylinders are arranged in the oil removal tank. The incoming water of the oil removal tank firstly evenly enters into a number of drive diversion cylinders, and then enters into the corresponding separation zone through the water outlet components of the drive diversion cylinders corresponding to each separation zone.

[0009] Optionally, the static settling tank is square, with an inlet pipe provided on the upstream side and an outlet pipe provided on the downstream side, the inlet of the outlet pipe facing the lower end of the lowest guide channel; the uppermost and lowermost guide channels are respectively arranged close to the other two opposite sides of the static settling tank, so that the inlet water is close to one vertex corner of the static settling tank, and the outlet water is close to another vertex corner on the diagonal line of the static settling tank;

[0010] An oil discharge port is provided at the top or upper part of the downstream side of the static sedimentation tank for discharging the oil phase obtained by static separation, a water production port is provided in the middle part for discharging the water phase obtained by static separation, and a slag discharge port is provided at the bottom of the static sedimentation tank for discharging solid waste deposited at the bottom.

[0011] Further optionally, the head of the flow guide channel is higher than the tail, and except for the top flow guide channel, the head of the flow guide channel is connected to the tail of the adjacent upper flow guide channel through a water outlet section; except for the bottom flow guide channel, the tail of the flow guide channel is connected to the head of the adjacent next flow guide channel through a water outlet section;

[0012] The tail of the flow guide channel is closer to the side of the water outlet pipe than the head, so that the plurality of flow guide channels are gradually transitioned from one side to another side;

[0013] The water flows in two adjacent guide channels in opposite directions and generally flow downward.

[0014] Further optionally, the longitudinal section of the water outlet section is the same as the longitudinal section of the guide channel, the water outlet section is arc-shaped as a whole, and the two ends of the water outlet section are respectively facing the upstream side and the downstream side of the static settling tank, so that the two ends of the water outlet section can connect with the adjacent upper and lower guide channels;

[0015] The upper and lower sides of the water outlet section are both closed, and the side facing the guide channel is also closed. A number of water outlet holes are evenly distributed on the side facing away from the guide channel, so that when the sewage changes the material flow direction in the water outlet section, part of the material can flow out from the water outlet hole 1.

[0016] Optionally, the oil removal tank is cylindrical, a first partition plate is provided between the primary separation zone and the secondary separation zone, a second partition plate is provided between the secondary separation zone and the tertiary separation zone, a plurality of driving diverter cylinders form a circle and are spaced the same distance apart from each other, and the circle is concentrically arranged with the oil removal tank; the bottom of the driving diverter cylinder is connected to the bottom of the oil removal tank, the driving diverter cylinder passes through the first partition plate and the second partition plate, and the top of the driving diverter cylinder is higher than the liquid level in the tertiary separation zone and is open.

[0017] Further optionally, the driving diversion cylinder is provided with a liquid inlet, a first rotating part, a first liquid outlet, a second liquid outlet, a second rotating part and a third liquid outlet from bottom to top, the first liquid outlet is located in the middle of the primary separation zone, the second liquid outlet and the second rotating part correspond to the range of the secondary separation zone, and the third liquid outlet corresponds to the range of the tertiary separation zone.

[0018] Further optionally, the motor of the first rotating part is arranged below the liquid inlet and is surrounded by a waterproof cover, and the rotating shaft of the first rotating part is arranged vertically, connecting the corresponding motor and the center of the impeller to drive the impeller to rotate;

[0019] The motor of the second rotating part is arranged above the liquid surface of the three-stage separation zone, or above the outside of the oil removal tank. The rotating shaft of the second rotating part is arranged vertically, connecting the corresponding motor and the impeller center to drive the impeller to rotate.

[0020] Further optionally, the first liquid outlet portion is a circle of water troughs surrounding the outside of the driving diverter cylinder, with a U-shaped longitudinal section, an open top, and a plurality of water outlets at the bottom, and the water outlets are evenly arranged along the circumference of the driving diverter cylinder; the part of the side wall of the driving diverter cylinder corresponding to the first liquid outlet portion is evenly and densely distributed with water outlet holes 2, so as to facilitate the discharge of water in the driving diverter cylinder to the first liquid outlet portion, and then from the first liquid outlet portion to the primary separation area.

[0021] Further optionally, the second liquid outlet portion is a circle of water troughs surrounding the outside of the driving diverter cylinder, with a U-shaped longitudinal section, an open top, and a plurality of water outlets at the bottom, and the water outlets are evenly arranged along the circumference of the driving diverter cylinder; the part of the side wall of the driving diverter cylinder corresponding to the second liquid outlet portion is evenly and densely distributed with water outlet holes 2, so as to facilitate the discharge of water in the driving diverter cylinder to the second liquid outlet portion, and then from the second liquid outlet portion to the secondary separation area.

[0022] Further optionally, the third liquid outlet portion is a circle of water troughs surrounding the outside of the driving diverter cylinder, with a U-shaped longitudinal section, an open top, and a plurality of water outlets at the bottom, and the water outlets are evenly arranged along the circumference of the driving diverter cylinder; the part of the side wall of the driving diverter cylinder corresponding to the third liquid outlet portion is evenly and densely distributed with water outlet holes 2, so as to facilitate the discharge of water in the driving diverter cylinder to the third liquid outlet portion, and then from the third liquid outlet portion to the three-stage separation area. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of the fracturing and produced water circulation and treatment system of the deep coalbed methane well in the coal mine field;

[0024] Figure 2 is a side view schematic diagram of a static sedimentation tank;

[0025] Figure 3 It is a top view schematic diagram of a static sedimentation tank;

[0026] Figure 4 is a schematic diagram of the water outlet section;

[0027] Figure 5 It is a structural schematic diagram of the degreasing pool;

[0028] Figure 6 It is a schematic diagram of the structure of the driving splitter cylinder;

[0029] Figure 7 A three-dimensional schematic diagram of the driving diversion cylinder.

[0030] In the attached drawings, 1-static sedimentation tank, 2-oil removal tank, 3-guide channel, 4-water outlet section, 5-water outlet hole 1, 6-water outlet hole 2, 7-primary separation zone, 8-secondary separation zone, 9-tertiary separation zone, 10-driving diversion cylinder, 11-water inlet pipe, 12-water outlet pipe, 13-upstream side surface, 14-downstream side surface, 15-liquid inlet, 16-first rotating part, 17-first liquid outlet part, 18-second liquid outlet part, 19-second rotating part, 20-third liquid outlet part, 21-main pipe, 22-branch pipe, 23-water outlet, 24-fracture water tank, 25-drainage tank. DETAILED DESCRIPTION

[0031] This embodiment provides a deep coalbed methane well fracturing and produced water circulation and treatment system in a coal mine field, such as Figure 1-Figure 7 As shown, it includes a recycling unit, an oil removal tank 2 and a biochemical treatment unit. The recycling unit includes a mine water treatment unit and a plurality of well water treatment units connected in series. The mine water treatment unit includes a static sedimentation tank 1 and a fracturing water tank 24 connected in series. The mine water discharged from the coal seam tunnel is discharged into the static sedimentation tank, and after treatment, it is discharged into the fracturing water tank, which can be used as fracturing water for the first coal seam gas well.

[0032] The well drainage treatment unit includes a reverse drainage tank 25, a static sedimentation tank and a fracturing water tank which are connected in sequence. The drainage water of the coalbed methane well is processed in the reverse drainage tank and the static sedimentation tank in sequence, and then discharged into the fracturing water tank, which can be used as fracturing water for the next coalbed methane well.

[0033] The discharge water pipe of the last coalbed methane well is connected to a static settling tank, an oil removal tank 2 and a biochemical treatment unit in sequence.

[0034] The above fracturing water pool and reverse drainage pool have the same structure, and both can be conventional water storage tanks. In the present invention, the mine water is processed in the static sedimentation tank, and then used as the fracturing water of the first coalbed methane well, and temporarily stored in a fracturing water pool for the first coalbed methane well fracturing. Then, the discharge water of each coalbed methane well enters the corresponding reverse drainage pool for preliminary precipitation, and then is discharged into the corresponding static sedimentation tank for treatment, and then temporarily stored in the corresponding fracturing water pool for the next coalbed methane well fracturing, until the last coalbed methane well. The discharge water of the last coalbed methane well is processed in turn by the corresponding static sedimentation tank, oil removal tank 2 and biochemical treatment unit, and can finally meet the reuse water standard.

[0035] Optionally, a plurality of inclined guide channels 3 are provided from top to bottom in the static sedimentation tank 1, which are zigzag and evenly arranged in the static sedimentation tank 1, and the guide channels are connected end to end; a water inlet pipe 11 is connected to the higher end of the top guide channel to input sewage into the static sedimentation tank 1; a water outlet section 4 is provided at the connection between two adjacent guide channels, and a water outlet hole 5 is provided on the side of the water outlet section 4 to discharge part of the water in the guide channel 3 to the static sedimentation tank 1 for oil-water-solid separation, and the other part of the water continues to flow to the next guide channel;

[0036] The oil removal tank 2 includes a primary separation zone 7, a secondary separation zone 8 and a tertiary separation zone 9 from bottom to top. A plurality of vertical driving diversion cylinders 10 are provided in the oil removal tank 2. The incoming water of the oil removal tank 2 first evenly enters into the plurality of driving diversion cylinders 10, and then enters into the corresponding separation zone through the water outlet components of the driving diversion cylinders 10 corresponding to each separation zone.

[0037] Optionally, the static sedimentation tank 1 is square, and an inlet pipe 11 is provided on the upstream side 13, and an outlet pipe 12 is provided on the downstream side 14, and the inlet of the outlet pipe 12 is directly opposite to the lower end of the lowest diversion channel; the uppermost and lowermost diversion channels are respectively arranged close to the other two opposite sides of the static sedimentation tank 1, so that the inlet water is close to one vertex corner of the static sedimentation tank 1, and the outlet water is close to another vertex corner on the diagonal line of the static sedimentation tank 1;

[0038] An oil discharge port is provided at the top or upper part of the downstream side surface 14 of the static sedimentation tank 1 for discharging the oil phase obtained by static separation, a water production port is provided in the middle part for discharging the water phase obtained by static separation, and a slag discharge port is provided at the bottom of the static sedimentation tank 1 for discharging the solid waste deposited at the bottom.

[0039] Further optionally, the head of the guide channel 3 is higher than the tail, and except for the top guide channel, the head of the guide channel 3 is connected to the tail of the adjacent upper guide channel through a water outlet section 4; except for the bottom guide channel, the tail of the guide channel 3 is connected to the head of the adjacent next guide channel through a water outlet section 4;

[0040] The tail of the flow guide channel 3 is closer to the side of the water outlet pipe 12 than the head, so that the plurality of flow guide channels are gradually transitioned from one side to another side.

[0041] The water flows in two adjacent guide channels in opposite directions and generally flow downward.

[0042] Further optionally, the side of the guide channel 3 is closed, and the longitudinal section of the guide channel 3 is circular, square, trapezoidal or triangular, so that the sewage can flow along the inside of the guide channel 3.

[0043] Further optionally, the longitudinal section of the water outlet section 4 is the same as the longitudinal section of the guide channel 3, the water outlet section 4 is arc-shaped as a whole, and its two ends are respectively facing the upstream side surface 13 and the downstream side surface 14 of the static settling tank 1, so that the two ends of the water outlet section 4 can connect the upper and lower guide channels;

[0044] The upper and lower sides of the water outlet section 4 are both closed, and the side facing the guide channel 3 is also closed. A number of water outlet holes 5 are evenly distributed on the side facing away from the guide channel, so that when the sewage changes the material flow direction in the water outlet section 4, part of the material can flow out from the water outlet holes 5.

[0045] Further optionally, a filter is provided on the upstream side of the water inlet pipe 11 to intercept solid impurities (such as rocks, stones, coal blocks, etc.) in the fracturing water and the produced water to avoid excessive impact on the diversion channel; a filter is also provided at the inlet of the water outlet pipe 12, and the solid waste in the material discharged from the lowest diversion channel is intercepted in the static sedimentation tank 1. The outlet of the water outlet pipe 12 is connected to the water inlet pipe 11 through a pipeline and a water pump, and the sewage after passing through each diversion channel is returned to the static sedimentation tank 1 through the water inlet pipe 11 and passes through the diversion channel again.

[0046] For sewage containing oil phase and solid waste, the traditional treatment method is static separation. The weight efficiency varies according to the content of the oil phase, but the general weight efficiency is not high, which is not suitable for large-scale water use in coal mining areas. The present invention optimizes the static separation tank, adds a number of folded, end-to-end guide channels, and the sewage after coarse filtration enters the top guide channel, and flows down along the guide channel and toward the downstream side 14 of the static sedimentation tank 1. When flowing down, it is beneficial for the solid waste in the sewage to quickly settle to the bottom surface of the guide channel, and quickly slide down along the bottom surface, promoting solid-liquid separation. When the material flows to the tail of the guide channel, it enters the corresponding water outlet section, and the material flow needs to change the flow direction in the water outlet section, from flowing toward the downstream side 14 to flowing toward the upstream side 13. The material flow flows and turns along the arc-shaped inner wall of the water outlet section. Due to the large turning angle (basically 180°), the material will generate centrifugal force, which acts on the side with the water outlet hole 1, and throws the material out of the water outlet hole 1. Due to the difference in deadweight, the solid is thrown out first, followed by the water phase, and finally the oil phase. The water outlet section is conducive to the separation of the three phases. However, the side with the water outlet hole 1 plays a filtering role, which makes the solid waste discharge unsmooth, and the water phase is not affected. A part of the solid waste is discharged from the water outlet hole 1, and the other solid waste flows to the bottom of the static sedimentation tank 1 with the material flow (realizing that the solid waste is directly sent to the bottom), and then intercepted by the filter net before the water outlet pipe 12, so that most of the solid waste stays at the bottom of the static sedimentation tank 1. Since the amount of material thrown out in a water outlet section is not large and is limited by the outlet hole, the impact of the thrown material on the original material in the surrounding static sedimentation tank 1 is minimized as much as possible, and the static separation is affected as little as possible. The total amount of material discharged in each water outlet section accounts for the percentage of the amount of material input by the water inlet pipe 11, which can be adjusted by the number of water outlet sections and the aperture and size of the water outlet hole 1.

[0047] The remaining material is discharged from the bottom guide channel. Although it has some impact on the material at the bottom of the static sedimentation tank 1, the discharged material can pass through the filter screen and be discharged into the corresponding outlet pipe 12, thereby minimizing the impact on the bottom of the static sedimentation tank 1. The material in the outlet pipe 12 has a low solid waste content and returns to the top guide channel through the inlet pipe 11, diluting the solid waste concentration of the newly-input material and promoting separation.

[0048] Optionally, the oil removal tank 2 is cylindrical, a first partition plate is provided between the primary separation zone 7 and the secondary separation zone 8, a second partition plate is provided between the secondary separation zone 8 and the tertiary separation zone 9, and a plurality of driving diverter cylinders 10 form a circle and maintain the same interval with each other, and the circle is concentrically arranged with the oil removal tank 2; the bottom of the driving diverter cylinder 10 is connected to the bottom of the oil removal tank 2, the driving diverter cylinder 10 passes through the first partition plate and the second partition plate, and the top of the driving diverter cylinder 10 is higher than the liquid level of the tertiary separation zone 9 and is open.

[0049] Further optionally, the driving flow dividing cylinder 10 is provided with a liquid inlet 15, a first rotating part 16, a first liquid outlet 17, a second liquid outlet 18, a second rotating part 19 and a third liquid outlet 20 in sequence from bottom to top, the first liquid outlet 17 is located in the middle of the primary separation zone 7, the second liquid outlet 18 and the second rotating part 19 correspond to the range of the secondary separation zone 8, and the third liquid outlet 20 corresponds to the range of the tertiary separation zone 9;

[0050] The water outlet of the static sedimentation tank 1 is connected to the liquid inlet 15 of each driving diverter cylinder 10 through a pipeline, and the water phase separated by the static sedimentation tank 1 is input into the driving diverter cylinder 10; the water flow is accelerated by the first rotating part 16 and rises to the first liquid outlet part 17, and part of the water flow is discharged from the first liquid outlet part 17 to the primary separation area 7 for oil-water separation; the remaining water phase continues to rise and is gradually affected by the second rotating part 19 to achieve sufficient stirring of the sewage, and is discharged from the second liquid outlet part 18 to the secondary separation area 8 for oil-water separation; the remaining water phase passes through the second rotating part 19 and continues to rise, and is finally discharged from the third liquid outlet part 20 to the tertiary separation area 9 for oil-water separation.

[0051] Further optionally, a water distribution part is provided at the bottom of the oil removal tank 2, and the center of the water distribution part is at the center of the circle at the bottom of the oil removal tank 2. The water distribution part includes a main pipe 21 and a plurality of branch pipes 22. The two ends of the branch pipes 22 are respectively connected to the outlet of the main pipe 21 and the corresponding liquid inlet 15 of the driving diversion cylinder 10. The water outlet of the static sedimentation tank 1 is connected to the inlet of the main pipe 21 through a pipeline. The plurality of branch pipes 22 are evenly distributed radially along the circle surrounded by the plurality of driving diversion cylinders 10.

[0052] Further optionally, the motor of the first rotating part 16 is arranged below the liquid inlet and is surrounded by a waterproof cover, and the rotating shaft of the first rotating part 16 is arranged vertically, connecting the corresponding motor and the center of the impeller to drive the impeller to rotate;

[0053] The motor of the second rotating part 19 is arranged above the liquid surface of the tertiary separation zone 9, or above the outside of the oil removal tank 2. The rotating shaft of the second rotating part 19 is arranged vertically, connecting the corresponding motor and the impeller center to drive the impeller to rotate.

[0054] Further optionally, the first liquid outlet portion 17 is a circle of water troughs surrounding the outside of the driving diverter cylinder, with a U-shaped longitudinal section, an open top, and a plurality of water outlets 23 at the bottom, and the water outlets 23 are evenly arranged along the circumference of the driving diverter cylinder; the side wall of the driving diverter cylinder corresponding to the first liquid outlet portion 17 is evenly and densely distributed with water outlet holes 6, so as to facilitate the water in the driving diverter cylinder to be discharged to the first liquid outlet portion 17, and then discharged from the first liquid outlet portion 17 to the primary separation area 7.

[0055] Further optionally, the second liquid outlet portion 18 is a circle of water troughs surrounding the outside of the driving diverter cylinder, with a U-shaped longitudinal section, an open top, and a plurality of water outlets at the bottom, and the water outlets are evenly arranged along the circumference of the driving diverter cylinder; the part of the side wall of the driving diverter cylinder corresponding to the second liquid outlet portion 18 is evenly and densely distributed with water outlet holes 2, so as to facilitate the water in the driving diverter cylinder to be discharged to the second liquid outlet portion 18, and then discharged from the second liquid outlet portion 18 to the secondary separation zone 8.

[0056] Further optionally, the third liquid outlet portion 20 is a circle of water troughs surrounding the outside of the driving diverter cylinder, with a U-shaped longitudinal section, an open top, and a plurality of water outlets at the bottom, and the water outlets are evenly arranged along the circumference of the driving diverter cylinder; the side wall of the driving diverter cylinder corresponding to the third liquid outlet portion 20 is evenly and densely distributed with water outlet holes 2, so as to facilitate the water in the driving diverter cylinder to be discharged to the third liquid outlet portion 20, and then discharged from the third liquid outlet portion 20 to the tertiary separation zone 9.

[0057] After three-phase separation in the static separation tank, most of the oil phase is separated out, and the water phase is input into the oil removal tank 2. At this time, the water phase and the oil phase exist in the form of emulsions, and static separation cannot achieve oil-water separation of this sewage. The present invention uses a rotation method to increase the water flow speed or flow rate, promote water agitation, increase the instability of the water body, and promote oil-water separation.

[0058] Specifically, the water at the bottom of the diversion cylinder is driven to be stirred by the first rotating part 16, and the rotation speed and flow rate are increased, the water flow is in a rotating upward state, and the emulsified state is disturbed or broken to a certain extent. When passing the position corresponding to the first liquid outlet 17, it is discharged from the water outlet hole 1 here into the first liquid outlet 17 under the action of centrifugal force, and continues to rotate along the inner wall of the first liquid outlet 17, while oil and water separation is performed, the oil phase is discharged from the top, and the water phase is discharged from the water outlet at the bottom. Due to the principle of communicating vessels, the first rotating part 16 is always full, and the oil phase and water phase newly discharged to the first rotating part 16 force the original oil phase to be discharged.

[0059] The remaining water flow in the diverter cylinder is driven to continue to rise and is gradually affected by the second rotating part 19. The second rotating part 19 rotates in the opposite direction to the first rotating part 16. The rising water flow is stirred more violently by the force of the water flow rotating in the opposite direction, and the emulsified state is continuously broken. At this time, part of the water flow is discharged from the water outlet hole 1 to the second liquid outlet part 18, and continues to rotate along the inner wall of the second liquid outlet part 18, while oil and water separation is performed, the oil phase is discharged from the top, and the water phase is discharged from the water outlet at the bottom. Due to the principle of communicating vessels, the second rotating part 19 is always full, and the new oil phase and water phase discharged to the second rotating part 19 force the original oil phase to be discharged. The remaining water flow in the diverter cylinder is driven to continue to rotate and rise through the second rotating part 19, and is completely discharged from the third liquid outlet part 20 to the third separation zone.

[0060] The oil phase and water phase discharged from each separation section to the corresponding separation zone continue to separate (away from similar static separation). The upper and lower parts of each separation zone are respectively provided with an oil discharge port and a water outlet. The oil discharge port of the separation zone and the oil discharge port of the static settling tank 1 are connected to the oil storage tank through a pipeline, and the water outlet of the separation zone and the water production port of the static settling tank 1 are connected to the water storage tank through a pipeline. After homogenization, it can be used as the inlet water of the biochemical treatment unit. After the degreasing operation of the static settling tank 1 and the degreasing tank 2, the organic matter in the water phase is greatly reduced, which reduces the compliance and treatment costs of the biochemical treatment unit.

[0061] According to the requirements for the reuse of circulating water, the form and operation process of the biochemical treatment unit are reasonably set. For example, the traditional AO or AAO form can be used, and anaerobic, anoxic and aerobic treatment can be combined to make the produced water meet the water requirements of fracturing water or drainage water in coal mining areas.

Claims

1. A deep coalbed methane well fracturing and produced water circulation and treatment system in a coal mine field, characterized in that It includes a recycling unit, an oil removal tank and a biochemical treatment unit. The recycling unit includes a mine water treatment unit and a plurality of well water treatment units connected in series. The mine water treatment unit includes a static sedimentation tank and a fracturing water tank connected in series. The mine water discharged from the coal seam tunnel is discharged into the static sedimentation tank, and after treatment, it is discharged into the fracturing water tank, which can be used as fracturing water for the first coal seam gas well. The well drainage treatment unit includes a reverse drainage tank, a static sedimentation tank and a fracturing water tank which are connected in sequence. The drainage water of the coalbed methane well is processed in the reverse drainage tank and the static sedimentation tank in sequence, and then discharged into the fracturing water tank, which can be used as fracturing water for the next coalbed methane well. The discharge pipe of the last coalbed methane well is connected to a static settling tank, degreasing tank and biochemical treatment unit in sequence; The static sedimentation tank is provided with a plurality of inclined guide channels from top to bottom, which are arranged in a zigzag and uniform manner in the static sedimentation tank, and the guide channels are connected end to end; the water inlet pipe is connected to the higher end of the top guide channel to input sewage into the static sedimentation tank; the connection between the two adjacent guide channels is provided with a water outlet section, and the side of the water outlet section is provided with a water outlet hole 1, which discharges part of the water in the guide channel to the static sedimentation tank for oil-water-solid separation, and the other part of the water continues to flow to the next guide channel; The oil removal tank includes a primary separation zone, a secondary separation zone and a tertiary separation zone from bottom to top. A number of vertical drive diversion cylinders are arranged in the oil removal tank. The incoming water of the oil removal tank firstly evenly enters into a number of drive diversion cylinders, and then enters into the corresponding separation zone through the water outlet components of the drive diversion cylinders corresponding to each separation zone.

2. The circulation and treatment system according to claim 1, characterized in that: The static sedimentation tank is square, with an inlet pipe provided on the upstream side and an outlet pipe provided on the downstream side, the inlet of the outlet pipe facing the lower end of the lowest diversion channel; the uppermost and lowermost diversion channels are respectively arranged close to the other two opposite sides of the static sedimentation tank, so that the inlet water is close to one vertex corner of the static sedimentation tank, and the outlet water is close to another vertex corner on the diagonal line of the static sedimentation tank; An oil discharge port is provided at the top or upper part of the downstream side of the static sedimentation tank for discharging the oil phase obtained by static separation, a water production port is provided in the middle part for discharging the water phase obtained by static separation, and a slag discharge port is provided at the bottom of the static sedimentation tank for discharging solid waste deposited at the bottom.

3. The circulation and treatment system according to claim 2, characterized in that: The head of the flow guide channel is higher than the tail. Except for the top flow guide channel, the head of the flow guide channel is connected to the tail of the adjacent upper flow guide channel through a water outlet section; except for the bottom flow guide channel, the tail of the flow guide channel is connected to the head of the adjacent next flow guide channel through a water outlet section; The tail of the guide channel is closer to the side of the water outlet pipe than the head, so that several guide channels are gradually transitioned from one side to another side; the water flows in two adjacent guide channels have opposite directions and generally flow downward.

4. The circulation and treatment system according to claim 3, characterized in that: The longitudinal section of the water outlet section is the same as the longitudinal section of the guide channel. The water outlet section is arc-shaped as a whole, and its two ends are respectively facing the upstream side and the downstream side of the static sedimentation tank, so that the two ends of the water outlet section can connect with the adjacent upper and lower guide channels; The upper and lower sides of the water outlet section are both closed, and the side facing the guide channel is also closed. A number of water outlet holes are evenly distributed on the side facing away from the guide channel, so that when the sewage changes the material flow direction in the water outlet section, part of the material can flow out from the water outlet hole 1.

5. The circulation and treatment system according to claim 1, characterized in that: The oil removal tank is cylindrical, with a first partition plate between the primary separation zone and the secondary separation zone, and a second partition plate between the secondary separation zone and the tertiary separation zone. A plurality of drive diverter cylinders form a circle and are spaced the same distance apart from one another, and the circle is concentrically arranged with the oil removal tank. The bottom of the drive diverter cylinder is connected to the bottom of the oil removal tank, the drive diverter cylinder passes through the first partition plate and the second partition plate, and the top of the drive diverter cylinder is higher than the liquid level in the tertiary separation zone and is open.

6. The circulation and treatment system according to claim 5, characterized in that: The driving diversion cylinder is provided with a liquid inlet, a first rotating part, a first liquid outlet, a second liquid outlet, a second rotating part and a third liquid outlet from bottom to top, the first liquid outlet is located in the middle of the primary separation zone, the second liquid outlet and the second rotating part correspond to the range of the secondary separation zone, and the third liquid outlet corresponds to the range of the tertiary separation zone.

7. The circulation and treatment system according to claim 6, characterized in that: The motor of the first rotating part is arranged below the liquid inlet and is surrounded by a waterproof cover. The rotating shaft of the first rotating part is arranged vertically, connecting the corresponding motor and the center of the impeller to drive the impeller to rotate; The motor of the second rotating part is arranged above the liquid surface of the three-stage separation zone, or above the outside of the oil removal tank. The rotating shaft of the second rotating part is arranged vertically, connecting the corresponding motor and the impeller center to drive the impeller to rotate.

8. The circulation and treatment system according to claim 6, characterized in that: The first liquid outlet portion is a circle of water troughs surrounding the outside of the driving diverter cylinder, with a U-shaped longitudinal section, an open top, and a plurality of water outlets at the bottom, which are evenly arranged along the circumference of the driving diverter cylinder; the side wall of the driving diverter cylinder corresponding to the first liquid outlet portion is evenly and densely covered with water outlet holes 2, so as to facilitate the water in the driving diverter cylinder to be discharged to the first liquid outlet portion, and then discharged from the first liquid outlet portion to the primary separation area.

9. The circulation and treatment system according to claim 6, characterized in that: The second liquid outlet portion is a circle of water troughs surrounding the outside of the driving diverter cylinder, with a U-shaped longitudinal section, an open top, and a plurality of water outlets at the bottom, which are evenly arranged along the circumference of the driving diverter cylinder; the side wall of the driving diverter cylinder corresponding to the second liquid outlet portion is evenly and densely covered with water outlet holes 2, which is convenient for discharging the water in the driving diverter cylinder to the second liquid outlet portion, and then from the second liquid outlet portion to the secondary separation area.

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